"You have heard that it was said to the people long ago, 'Do not murder, and anyone who murders will be subject to judgment.' But I tell you that anyone who is angry with his brother will be subject to judgment...
"Therefore, if you are offering your gift at the altar and there remember that your brother has something against you, leave your gift there in front of the altar. First go and be reconciled to your brother; then come and offer your gift." (Matthew 5:21-22, 23-24)
We all know that Christians aren't perfect. Of course we aren't--we're all human! We are covered in the blood of the Lamb, which makes us a fit offering to God despite our iniquities, but we must always remember that we on earth are not perfect. We may not even be "mostly good." Essentially, we're a bunch of misfits and sinners whom God has called to His Kingdom anyway.
And because we're not perfect, we're going to hurt and take advantage of each other. It may not be deliberate, but it will happen. And we are going to be hurt and taken advantage of, sometimes by our closest friends or even our Christian leaders!
So what do we do about it? Do we allow ourselves to get angry? Do we allow ourselves to talk to other people about it? Do we allow ourselves to imagine what we would like to say to the other person, even if we know we never would? Do we crucify them in our hearts?
This passage above is a hard one. I mean really, Jesus is saying that if we harbor ill will or resentment against someone, if we think less of them as a person and hold onto anger, then we have actually committed the sin of murder! Suddenly that list of ten things you're never supposed to do is reduced by one. "Well shoot, murder was the one thing I figured I had a free pass on, since I never plan to actually kill anyone." (Well and if that gets ya, keep reading Matthew to see what Jesus says about adutery. Yikes!)
So what must we do about these situations? How do we become reconciled to our brother or sister? I believe that this is the most important step of all, one I'm honestly still figuring out. But in order to reconcile, you must come to the table with certain things clear in your mind: A) The actual problem that exists B) A thorough understanding of the other person's position (as much as possible without yammering to other people about your issue) C) An aknowledgement of what you have done to create or perpetuate this problem D) The truths from which you will not be swayed and E) The areas where you are willing to admit guilt/wrong or responsibility, even if they are not the biggest part of the issue.
Then you pray. You pray that God will open your heart to hear theirs through their words. You pray that God will give you clarity in thought and the ability to stand firm about that which is undeniable, and to yield when it serves the greater purpose of reconciliation. If you need to enlist the aid of a friend or mentor that is perfectly acceptible--perhaps you simply ask them to keep you in prayer while you deal with reconciling with someone, and perhaps you let them know the entire situation and also ask for their guidance. As long as this is a healthy Christian who will not spread rumors, this is perfectly acceptible. But it is most important to as God for His guidance.
And then? Then you talk to the other person. Face-to-face or on the phone, whatever you can do to at least hear each other's voice. And you do your best. And you make the goal to come out reconciled heart-to-heart, if not mind-to-mind. For you do not have to agree on everything for the conversation to be sucsessful. You just have to resolve your issues and understand that both you and the other person are ready and able to leave it behind, and move on towards a new day. And then, then you pray again, that God would seal it in your hearts.
At least, I sure hope this is the way to do it. :)